Introduction

FFmpeg is the universal multimedia toolkit: a complete, cross-platform solution to record, convert, filter and stream audio and video. It is used by a number of media players (including VLC, MPlayer, and Totem through GStreamer), video distribution websites (including YouTube and Vimeo), Internet browsers (including Google Chrome/Chromium), and lots
of other software projects in the multi-media field and beyond.

Information for Students

Getting Started

Get to know FFmpeg. If you are a student interested in contributing to FFmpeg, it is recommended to start by subscribing to the ​ffmpeg-devel mailing-list, visiting our FreeNode IRC channels (#ffmpeg-devel and #ffmpeg although you will find most developers on the first one), and exploring both the codebase and the development workflow. Feel free to contact us if you have any questions.

Find a project. Listed on this page are mentored and un-mentored projects. Mentored projects are well-defined and mentor(s) have already volunteered. Un-mentored projects are additional ideas you may want to consider, but you will have to contact us to find a mentor. You can also propose your own project, if you can think of one that better fits your interest and skill level. If a project description is unclear or you have any questions, please get in touch with its mentor and/or send an email to the program admins at [​opw@ffmpeg.org].

Contact us. If you decide on a project, get in touch with the community and let us know. If you want to work on a qualification task, let the respective mentor know so we can avoid duplicated efforts.

Apply. Students should apply by March 27 at the very latest. The "work" period begins on May 25 and ends in August. Take a look at ​GSoC timeline for additional information.

Note: A friendly reminder that while the application to GSoC is important for you and GSoC, FFmpeg mentors will not base their decision solely on the GSoC application. We will judge the applicant based on their abilities in coding, learning the tools, communication skills etc. So please do not worry about your application being perfect for us. Although it is very important to follow GSoC's application rules so they can pay you.

Qualification Tasks

In order to get accepted you normally have to complete a small qualification task. FFmpeg development can be quite challenging and the qualification task helps us figure out whether you are motivated enough and have the potential to deliver successfully.

The qualification tasks are usually shown in the project description. Contact the respective mentor(s) for assistance on getting a related qualification task or if you want to propose your own. You can also browse the ​FFmpeg Bug Tracker for qualification task ideas. In general qualification tasks should include submitting a patch to the ffmpeg-devel mailing list which passes review and is accepted into the FFmpeg codebase. It will be common for such patches to need multiple iterations of submissions and reviews, so dont wait too long with the first submission!

Note: The running status of this term's qualification tasks is tracked here?.

Contacting FFmpeg

If you have questions or comments feel free to contact us via our mailing list, IRC channel, or e-mail one of the FFmpeg GSoC admins:

You may also contact a mentor directly if you have questions specifically related to one of the projects listed on this page.

Mentored Projects

This section lists well-defined projects that have one or more available mentors. If you are new to FFmpeg, and have relatively little experience with multimedia, you should favor a mentored project rather than propose your own. Contact the respective mentor(s) to get more information about the project and the requested qualification task.

Animated Portable Network Graphics (APNG)

Description: Add encoding support for Animated PNGs. The little bouncing ball animation shown to the right is such an APNG file.

FFv1 P frame support

Description: FFv1 is one of the most efficient intra-only lossless video codecs. Your work will be to add support for P frames with motion compensation and motion estimation support (the existing motion estimation code in libavcodec can be reused here). Then fine-tune it until the best compression rate is achieved. This will make FFv1 competitive with existing I+P frame lossless codecs like lossless H.264.

Expected results: State of the art P frame support in the FFv1 encoder and decoder implementation.

Postproc optimizations

Description: FFmpeg contains libpostproc, which is used to postprocess 8x8 DCT-MC based video and images (jpeg, mpeg-1/2/4, H.263 among others). Postprocessing removes blocking (and other) artifacts from low bitrate / low quality images and videos. The code though has been written a long time ago and its SIMD optimizations need to be updated to what modern CPUs support (AVX2 and SSE2+).

Expected results:

Convert all gcc inline asm in libpostproc to YASM.

Restructure the code so that it works with block sizes compatible with modern SIMD.

Add Integer SSE2 and AVX2 optimizations for each existing MMX/MMX2/3dnow optimization in libpostproc.

MPEG-4 Audio Lossless Coding (ALS) encoder

Description:
A MPEG-4 ALS decoder was implemented several years ago but an encoder is still missing in the official codebase. A rudimentary encoder has already been written and is available on ​github. For this project, that encoder is first to be updated to fit into the current codebase of FFmpeg and to be tested for conformance using the ​reference codec and specifications. Second, the encoder is to be brought through the usual reviewing process to hit the codebase at the end of the project.

Expected results:

Update the existing encoder to fit into the current codebase.

Ensure conformance of the encoder by verifying using the reference codec and generate a test case for ​FATE.

Ensure the FFmpeg decoder processes all generated files without warnings.

Enhance the rudimentary feature set of the encoder.

Prerequisites: C coding skills, basic familiarity with git. A certain interest in audio coding and/or knowledge about the FFmpeg codebase could be beneficial.

Hardware Acceleration API Software / Tracing Implementation

Description: Our support for hardware accelerated decoding basically remains untested. This is in part due to FFmpeg only implementing part of the required steps, and in part since it requires specific operating systems and hardware.

The idea would be to start with a simple stub implementation of an API like e.g. VDPAU that provides only the most core functions. These would then serialize out the function calls and data to allow easy comparison and regression testing. Improvements to this approach are adding basic input validation and replay capability to allow testing regression data against real hardware. This would be similar to what ​apitrace does for OpenGL.

A further step would be to actually add support for decoding in software, so that full testing including visual inspection is possible without the need for special hardware.

Prerequisites: C coding skills, basic familiarity with git

Qualification Task: Anything related to the hardware acceleration code, though producing first ideas and code pieces for this task would also be reasonable

Missing AAC decoder features

Description: FFmpeg contains an AAC decoder which is missing some features. The task is to rebase existing implementations to the current FFmpeg code-base, test them and fix the remaining bugs.

AAC BSAC decoder: This has already been started, but the existing decoder still fails on many samples

AAC SSR decoder

AAC 960/120 MDCT window

Qualification Task: See the ​FFmpeg bug tracker for AAC issues, fixing one of them or rebasing the existing incomplete BSAC decoder for current git head and fixing one or more existing bugs are possible qualification tasks.

AAC Encoder Improvements

Description: Currently, FFmpeg contains an experimental native AAC encoder (native meaning that it doesn't depend on external libraries), but it is lacking in terms of extension support, since it currently only implements AAC-LC (the low-complexity profile). Extending feature support of FFmpeg's native encoder is needed to make it competitive with other encoders.

MXF Demuxer Improvements

Essence in MXF is typically stored in one of two ways: as an audio/video interleave or with each stream in one huge chunk (such as 1 GiB audio followed by 10 GiB video). Previous ways of telling these apart have been technically wrong, but worked and we lack samples demonstrating the contrary.

Expected results: The sample in ticket ​ticket #2776 should demux correctly. Add a test case in ​FATE. The solution should grow libavformat by no more than 32 KiB.

Prerequisites: C coding skills, basic familiarity with git.

Qualification Task: Investigate if there may be a compact way of representing the UL -> WrappingKind mapping specified in the ​official RP224 Excel document. The tables takes up about half a megabyte verbatim which is unacceptable in a library as large as libavformat.

VDPAU filter

Description: VDPAU is not only about hardware-accelerated decoding but also allows some postprocessing - most notably deinterlacing. Other features of the API include scaling, noise removal, and a sharpening filter.

Expected results: Implement a filter that allows usage of the postprocessing features as defined by the VDPAU API. This should particularly include the deinterlacer, and ideally all features should be usable to allow comparing the quality and performance of different hardware and hardware vs. software.

Prerequisites: C coding skills, and you will need hardware that allows VDPAU post-processing.

Qualification Task: Show that you are familiar with the FFmpeg filter system by implementing a very simple inverse telecine filter under LGPL that allows reversal of the effect of the telecine filter.

Basic servers for network protocols

Description: libavformat contains clients for various network protocols used in multimedia streaming: HTTP, RTMP, MMS, RTSP. Your work will be to implement the server side for one or several of these protocols.

The libavformat framework is not designed to build general-purpose server applications with several clients, and nothing similar to the configuration features of real servers like Apache is expected, but libavformat should be able to stream a single predefined bytestream to/from a single client.

Note: server support is already implemented for the receiving side of RTSP.

Qualification Task: proof-of-concept server for one of the protocol, capable of interacting with a particular client in controlled circumstances; or anything network-related, e.g. fixing a ticket in our ​bug tracker.

TrueHD encoder

Description: FFmpeg currently does not support encoding to TrueHD, one of the lossless audio formats used on Bluray discs. A nearly functional Meridian Lossless Packing (MLP) encoder has already been written and is available on ​github. The MLP codec is the basis for TrueHD. For this project, that encoder is first to be updated to fit into the current codebase of FFmpeg and to be tested for conformance against Surcode's MLP encoder. Second, the encoder is to be updated to implement TrueHD functionality, allowing it to losslessly encode audio to play it on hardware devices capable of TrueHD decoding. Finally, the encoder is to be brought through the usual reviewing process to hit the codebase at the end of the project.

Expected results: a TrueHD encoder that allows to losslessly encode audio to play it on hardware devices capable of TrueHD decoding with a competetive compression rate

Prerequisites: C coding skills, basic familiarity with git

Qualification Task: Update the MLP encoder so that it produces a valid bitstream that can be decoded by FFmpeg without errors to silence. Find out how to validate the generated bitstream besides using FFmpeg.

Implement full support for 3GPP Timed Text (movtext, QuickTime?) subtitles

The standard subtitle format used in MP4 containers is 3GPP timed text, as defined in 3GPP TS 26.245. It is the only subtitle format supported in Apple's media players on OS X and iOS, and the only format that's part of the mpeg4 standard. As such it is important for FFmpeg to support the format as fully as possible. Currently, it supports a limited subset of the format without any rich text formatting or the ability to position text on the screen. For this project of the goal would be to implement complete support for these features and have the implementation fully reviewed and merged into FFmpeg.

Expected Results:

Prerequisites: C coding skills, basic familiarity with git, access to a video player with full support for these subtitles (eg: OS X QuickTime? player)

Unmentored Projects

This is a list of projects that students are encouraged to consider if a mentored project is unavailable or not within the students skill or interests. The student will have to find a mentor for the project. A student can also propose their own project.

VC-1 interlaced

Description: The FFmpeg VC-1 decoder has improved over the years, but many samples are still not decoded bit-exact and real-world interlaced streams typically show artefacts. This task is difficult.

Expected results:

Implement missing parts of interlacing

Make more reference samples bit-exact

Prerequisites: C coding skills, basic familiarity with git

Qualification Task: Find a bug in the current decoder implementation and fix it.

JPEG 2000

Description: FFmpeg contains an experimental native JPEG 2000 encoder and decoder. Both are missing many features, see also the FFmpeg bug tracker for some unsupported samples. This task is difficult

Expected results: A jpeg 2000 decoder which can decode most lossy samples without artifacts and lossless samples exactly.

Qualification Task: Fix an issue (for example from the bug tracker) to show that you are capable of improving the codec implementation.

Hardware Accelerated Video Encoding with VA-API

Description: FFmpeg already supports hardware accelerated decoding for multiple codecs but still lacks support for hardware accelerated encoding. The aim of the project is to add support for encoding with VA-API specifically, while keeping a generic enough approach in mind so that other hardware accelerators (TI-DSP, CUDA?) could be supported as well. This means that new hwaccel hooks are needed and two operational modes are possible: either (i) driver or hardware pack headers themselves, or (ii) lattitude is left to perform this task at the FFmpeg library level.

Qualification Task: Anything related to the Hardware Acceleration (hwaccel) API, or to its related users. e.g. port VDPAU acceleration to use hwaccel, add JPEG decoding support with VA-API, etc.

Mentor: TBA

Backup Mentor: TBA, possibly Tushar Gohad

H.264 Multiview Video Coding (MVC)

Description: MVC samples exist and the codec is used on Blu-ray media, but FFmpeg is missing a decoder. Since this project also consists of some changes in the current architecture, it is especially important that this project is discussed on the ffmpeg-devel mailing list.

Browsing content on the server

The libavformat framework is able to read, seek and write to files located on server as they were local files. The libavformat is not able to list files nor directories located on remote servers.
Your work will be to implement browsing files on remote servers.

Note: the libavformat will be prepared with suitable API and only protocol related code will need to be implemented.

Expected results: Application that uses libavformat will be provided with an API to list files and directories (with their attributes like size, creation date, etc) located on remote servers. Implementation for FTP, HTTP and SFTP is required. Optionally file protocol can be also implemented.

Subtitles

Description: FFmpeg has been working on improving its subtitles support recently, notably by adding the support for various text subtitles and various hardsubbing (burning the subtitles onto the video) facilities. While the theme may sound relatively simple compared to audio/video signal processing, the project carries an historical burden not easy to deal with, and introduces various issues very specific to its sparse form.

Expected results:

Add support for new subtitles formats. Example: a VobSub muxer, a demuxer and decoder for EBU-TT, or even Kate subtitles (Xiph).

Improve text subtitles decoders. Typically, this can be supporting advanced markup features in SAMI or WebVTT.

Proper integration of subtitles into libavfilter. This is the ultimate goal, as it will notably allow a complete subtitles rendering for applications such as ffplay.

Prerequisites: C coding skills, basic familiarity with git. Some background in fansubbing area (notably ASS experience) would be a bonus but is not strictly required.

Qualification Task: write one subtitles demuxer and decoder (for example support for Spruce subtitles format). This is in order to make sure the subtitles chain is understood.

Your Own Project Idea

A student can propose a project. Ideas can also be found by browsing bugs and feature requests on our bug tracker. The work should last the majority of the GSoC internship duration, the task must be approved by the developers, and a mentor must be assigned.

Students can discuss an idea in the ffmpeg-devel mailing-list, the #ffmpeg-devel IRC channel, or contact the FFmpeg GSoC admins for more information.